n8n Workflow: Supabase Outreach Scheduler with Twilio & Retell

Automatically schedule and send outreach SMS or voice calls from Supabase—with Twilio & Retell

This n8n workflow runs every 15 minutes to claim due outreach enrollments from Supabase, decide the next message or voice touch (respecting sequence rules and quiet hours), send via Twilio (SMS) or Retell (voice), and then writes attempt outcomes and enrollment updates back to Supabase—optionally posting a summary to Slack.

What this workflow does

• Runs on a schedule (or on demand): executes every 15 minutes, loading configuration that controls the outreach sequence, quiet hours, caps, and provider settings.
• Claims due outreach from Supabase: uses an RPC call to pull a batch of due attempts; if Supabase isn’t configured, it can fall back to a built-in sample queue.
• Selects the next ladder step & content: evaluates each due enrollment, determines the next step, renders SMS body / voice-call variables, and generates an idempotency key to prevent duplicate sends.
• Enforces quiet hours and caps: applies candidate-local quiet hours/weekend rules and daily limits before attempting delivery.
• Sends or previews: routes items to Twilio for SMS or Retell for outbound voice calls; if sending is disabled, it outputs a preview of what would be sent.
• Handles outcomes and retry logic: classifies provider responses (sent, transient failure, permanent failure including carrier opt-outs) and advances, retries later with backoff, or stops the enrollment.
• Persists results back to Supabase: writes contact attempts, enrollment state updates, and carrier opt-outs when database writes are enabled.
• Posts Slack run summaries (optional): sends an incoming webhook message when Slack is configured and there’s something noteworthy to report.

Use cases

• Turn Supabase “due outreach” records into timely SMS follow-ups with Twilio.
• Run a mixed-channel outreach ladder where SMS and Retell voice touches occur in sequence.
• Prevent unwanted texting during quiet hours using candidate-local rules and daily caps.
• Maintain accurate outreach state, retries, and opt-out handling in Supabase.

Technical details

• n8n nodes: if, code, no op, merge, sticky note, http request.
• Integrations: Supabase (RPC claim + writes), Twilio (SMS), Retell (voice), Slack (incoming webhook summary).